Torsion axles are used on vehicles, such as trailers, for mounting wheels in order to provide suspension. These torsion axles include a torsion bar coupled to a shock absorbing mechanism which allows the wheel to move vertically in response to variations in terrain. One prior torsion axle design can be seen in U.S. Pat. No. 4,966,386, the contents of which are hereby incorporated by reference.
These torsion axles provide several benefits over commonly used spring axles. For example, their attachment mechanism provides additional strength to the trailer, adjustable (and lower) heights of the trailer, and better shock absorption.
Torsion axles generally work well when used in a single axle application on a trailer. In some circumstances, trailers must support higher loads. Often, additional axles are added to a trailer to support such loads. Double axles also generally work well, but can be subject to higher loads beyond an axle's rating (e.g., climbing a curb or hitting a large pothole). Additional loads can be created during sharp turns with a double axle since the pivot point is typically between both wheels of the double axle.
Triple axles are also possible for supporting very large loads. For example, if a 21,000 lb load must be supported, a trailer may incorporate three 7,000 lb torsion axles. However, the large load is rarely distributed evenly among the axles causing loads far greater than the rate capacity of an individual axle. In addition, the three axle application creates excessive side loads as a trailer performs sharp turns, usually backing, which, as the trailer pivots on the center axle, can scuff or drag the fully loaded front and rear tires across the road surface creating excessive side loads which tend to pull the torsion axle apart and damage wheels and tires. Using standard single axle designs in a three axle combination can lead to performance that is far inferior to that of a single axle. In this invention the three axle application is addressed with a “triple axle system” comprised of three specifically created axles design to work together as a unit in order to provide longer product life, safer product performance, and a smoother ride with loaded as well as unloaded loads.